/*-------------------------------------------------------------------------
 *
 * src/port/pgcheckdir.c
 *
 * A simple subroutine to check whether a directory exists and is empty or not.
 * Useful in both initdb and the backend.
 *
 * Portions Copyright (c) 1996-2017, PostgreSQL Global Development Group
 * Portions Copyright (c) 1994, Regents of the University of California
 *
 *-------------------------------------------------------------------------
 */

#include "c.h"

#include <dirent.h>


/*
 * Test to see if a directory exists and is empty or not.
 *
 * Returns:
 *        0 if nonexistent
 *        1 if exists and empty
 *        2 if exists and contains _only_ dot files
 *        3 if exists and contains a mount point
 *        4 if exists and not empty
 *        -1 if trouble accessing directory (errno reflects the error)
 */
int
pg_check_dir(const char *dir)
{// #lizard forgives
    int            result = 1;
    DIR           *chkdir;
    struct dirent *file;
    bool        dot_found = false;
    bool        mount_found = false;
    int            readdir_errno;

    chkdir = opendir(dir);
    if (chkdir == NULL)
        return (errno == ENOENT) ? 0 : -1;

    while (errno = 0, (file = readdir(chkdir)) != NULL)
    {
        if (strcmp(".", file->d_name) == 0 ||
            strcmp("..", file->d_name) == 0)
        {
            /* skip this and parent directory */
            continue;
        }
#ifndef WIN32
        /* file starts with "." */
        else if (file->d_name[0] == '.')
        {
            dot_found = true;
        }
        /* lost+found directory */
        else if (strcmp("lost+found", file->d_name) == 0)
        {
            mount_found = true;
        }
#endif
        else
        {
            result = 4;            /* not empty */
            break;
        }
    }

    if (errno)
        result = -1;            /* some kind of I/O error? */

    /* Close chkdir and avoid overwriting the readdir errno on success */
    readdir_errno = errno;
    if (closedir(chkdir))
        result = -1;            /* error executing closedir */
    else
        errno = readdir_errno;

    /* We report on mount point if we find a lost+found directory */
    if (result == 1 && mount_found)
        result = 3;

    /* We report on dot-files if we _only_ find dot files */
    if (result == 1 && dot_found)
        result = 2;

    return result;
}
